Centralizer interlocking control for multistage compressors



I '1623,494 Apr!! 1927' s. B. RIEDFIELD V CENTRALIZER INTERLOCKING CONTROI.- FOR MULTISTAGE COMPRESSOR'S Fil d Oct. 30. 1926 5 seets-she t V 96 59 47 97 96 f .5.5 27

Q Q Q o o m O o .R`-` &6 i z:

O 0 Q g O 0 (7 \O O O;

IN VEN TOR A ril 5 1927. v

p s; B. REDFlELD CENTRALIZER INTERLOCKING CONTROL FOR MULTISTAGE COMPRESSORS Filed- 001.30, 1926 s Sheets-S heet 3 INVEN-OR Aprl 5, 1927, 1623,494=

s. B. REDFIELD CENTRALIZER INTERLOCKING CONTROL FOR MULTISTAG COMPRESSOR. I

' Filed Oct. o, 1926 5 shets -sheet 4 5 av Z e ,4

I TO 4 i 5/ A BY 1775' A T RNEY,

V I 1,623,494 p s. B. REDFIELD CENTRALIZER INTERLOCKING CONTROL FOR MULTISTAGE COMPRESSORS Filed Ot. so, 1926 5 Sheets-Sheet 5 INVENTOR no e B or eaz Patente cl Apr .5, 1927. 4

v emt-e i se Me s "ee-t m.

%NOW-BEN B. REDFIELD, EASTON, PENNSLVANIA, ASSIGNORS TO INGER SOLL- RAE-ID COMPANY, OF JERSEY CITY, NEW' A CORPORATION OF NEW JERSEY CENTRALIZER INTERLCCKING ooNTno L' FOR MULTISTAGECOMPRESSOIRSL Application filedoctobet 30, 1926.. Serial No. 145343;

'This invention relates to conpressorS, but more pa'tcularly to an unloadng devce foicompressors of the nult-stage type.

The objects of the inventon are to enable the ,cylinders of the conpresso" to be se1ectively load-ed and unloaded hyfiuidectuted` ''eanswhenever it s desrable to-chenge the' Capacity or the workingpressure, to con-` Venently group the Valves which control the admission and -exhaust of pressure fluid to and' from the load controllin means, and to rendor the cotrlling n'echanism inter looking, so that in unloadng cylinder's'operating atloWer pressures, another cylind er Operating at a higher presure Will he simul taneously partally unloaded to coinpensate 'o' the reducton in the discherge Volume, of the lower pr-e'ssnre cylndei's, also to prevent conpresso* having the nvention epplied thereto, i

Figure 2 is a' top plan View of the conip e'esor,

Figu'e 3 is a 'sectional elevation pal-fly diag'emmetlc taken on the line 'El-&otFigm'e 2 looking in the direction` ofthe arroivs,

ot a portion of the third stage'oylinde' and its'controlling n echanisn, V

Figure 5' is a' sectoalelevztio'n of th fourth stage cylinder and its conti'olling Valve, i

Figure 6 is a sect-ional View o'fthe throttle valve and its handle takenthi'ough Figure '1 on the line 6-6 looking in' the direction of' the arrows, and FignI'eTis an enlarged de tal vew of one ofthe nlet VelVes and' ,its nnloader piston.

'feri-ing to the draWings,`-the invention- .is shown einhodied in atonipressof desi? 'noted generally by A. The compressor llstret-ed lsof the nnltbstege type conmonly I the ntercooler IL to a p'ressure suitable for used in marin-e craft as for instance; sub'- Figure 4 is an enlarged-seetiona'l elevation niarinesin which a 'portion of the con1- pressed air is ntlized by the .engines of the submarine and' a, portion: of the presente fluid 's compressed, to whgher p essu'efo' cha'ging the torpedo bottles. The conpres: so'*` A; 111 this lnstance has a pair* ofcylind'ers B and G preferably a''anged side hy side and nounted on suitable base 'pletes D= and E respectvely.

Within the cylnder B a pisten F to divde said cylinder' into' first and second' stage cylinde' chamhers G and H respectvely; r In' like nanner' a pisten F is pre Vded for the cylinder C to dvde said 'cyinden into a first stagecylinde'r che'nher J and a; second stage cylinder chambe'rl in the upper and' lower ends respectvely of'the cylnder' C. `The Pistons F may' he driven by any* suitable prime iover to 'whcli they mey he conneotedby connected'rods L operztively'conneoted to the Pistons by piston' The admssion of atnospheric air flowingthrough intake pipes 2-to the fi rst stage l t inder ehamhers G and'J is efi'ectedthroiighg type seated in ValVe boxes Rend Ssnpported' in this instance hy the cylinders`B and C- respectively., The aii" draW nj intojthe first stage-cylinders is conpressedhy thepistons F and is discharged through plate discharge i vehtes Tend U also seated'n the valVe boxes" inlet plte Val 'es P' and Q' of; anysuitable R and S respectively. The air thus' co1n`- pressed n the fii'st'stage eyhndens passes into a nanfold V nterposed between the `Velve boxes R and-Si and thence; through a pipo XV into an inte'cooler X;

'Picssiii'e fhd* from the intercooler X is Convey-ed the'eti'on'i hy a ppe Y having-` brune-hes Z andb which lead to the second stage ylindei' chanbers H* and K respectively; The ao'ission of presente fluid' into the second stage cylinoer chemhers H' and" K is controlled by hletiplate vlves bend 'd of a well known type." Dschzrge ple ge Valves Tend s U which' control 'the .exhzmft of pressur-e fluid fron the cylinder cha nhers H and K into 'chanh'ei s' e fol-med nsthe cyl inders B and C from Whence the pr essure fluid may pass through a`.ppe fWhich connects the'cha'mhers'e andthence through a' pjipe g into an intercooler h;

Tnorder to compress the pressure fluid in i *usein' nieehanisn -requiringfiuid of higher pressure such as internal co nbustion enginesgin fwhich" the; fuel' is injectedinto the combustion' chainher under pressure, a third i stage cylinder'j is arranged in tandem with; ,the'eylinderGend infth'is instance is shown' y. as being forinedintegrally with' the valve e 7 box S. e The cylinderj I is; in communication l ith theintercooler-fk through a pi'pe Ic and ;the adniission'of pressurej fiidromthepipe 76 iiito the cylinderfjis controlled by inlet l'plate. valve o seated; in a headjp supported; -by the` oylinder i ,The pressure fluid thus i entering the eylinder co npressed thle'ein to; ahigher pressure hy a pisten q connected 70,01 'as s ho}\'vn, p forned integrallv with the i I 'pisten lin the cylinder i and is dischar'gd g fthrhugh. discharge val v 73, a passage in the headfp; and thencej through a condut t intoflan intereooler 'cvlinderjfef and the ldischarge valve controls an eXhau-st passage fornied in the head e for-conveyng the exhaust pressure fluid from the cylinder v.

' In; ordrto'provde anovel and simple 'controlhngmeans for loading and unloadng ,i the several.cyliriders-Of the compressor, the inlet valves P and Qef the first stage cylin- ;der ch'anhers Gr and J are in this ;instance provided with unloader pistons 7 slidable'n coversfS seated onthe ;valve boxes Rand S.-

j The junlo'ad'ing'ipistons'have depending fin- ;gers 9`whieh,- when the istons 7 are in their 1",noperative postions eXtend to 'a point slightly removed-froni the va lve plateslo of ?the valves, P and Q.

Similar meansare provided torthe valves cend (Z in thecylinder chainbers H and K, ;although in this instance the pistons 7 are ;guided rin housings ll interposed between' theinlet valves and covers 12 which form ielosures forgthe housings'll. The unloading ;pistons 7 are of a well known type in which springsr B 7) are'provided for 'normally' holdingthe fingers 9"out of' contactwith the Valve'platejs 10, i

" i Pressure fiuidfor actuating the pistons 7 is conveyed to the cylinders wherein the said pistons 7 'reciprocateby a: pipe 13 having 7 branchesj and 15 connecting the pipe 13" with thegpstons which control the nlet "chestl ismounted. e

Convenient means are provided for 1na-- valves Q, and d; The pipe 13 in thisinstance leads from a valve chest 16 in whichis arranged a manipulatingvalve. 17 for 0011- pipe lS ntothe said pipe 13. In like inanner a. pipe 19 is provided-for conveying pres sure fiuid froni the valve chest ,16 to the un loader pistons 7; which control the inletv valves P and c' of the cylinder. chainhers G and H. i

may also be partly unload-ed whenever the ftrollingtheadmissionof air froni& service Inbrderltht thejthird stage oylinders j chambersof the cyl inder B or C are une loaded, a clearance valve 20 is arranged slidably-n;a'valve guide 21 inserted inthe head pito control a port 22 inthe oylinder A distance piece' 23 's in ths nstance. Secured to the valve guidepl and suppots at'its i' outer end a cylinder %in which is arranged i afiuid aetuated piston z 'adaptedto hear againsta stan 26 of the clearancevalve 20 for holdingthe said cl'earanee valve closed during' the loadedperiod of the'cylinder Pressure fluid for actueting the piston and thus also the v alve 201is conveyed to the cylinder 2& through a 'pipe 27 leading "from the valve chest 16. The achnission of;

pressure fiuid to the pipe 27 is also con trolled by 'the inanipulating valve 17, the ppe27 being so connected to the chest 16 .that-when 'the'two first stage, the two second stage and the third stagecylnders are Operating under ;tull load conditions,;there`,

will bea constant adnission of pressure fluidfrom thepipe 118 through a passage '28 in the valve 17and through the pipe 27 into. the cylinder 24. r i

valve 17' is provided with a'side, recess 29 which, when the manipulating valve is turned in` one direction, Will establish communication between the pipe 18 and a pas- In the present instanc'e the nanipulating i sage' 30fleading to the pipe 19.] A similar r c recess 31 is formedin the opposite side of the manipulatng valve 1'7 for establishing communication between the pipe 18 and the pipe 13 when the manipulating valve 17 is" turned to another liniting position.

The positions which ;the manipulating valve 17 may occupy for adintting pressure fluid froni the pipegl to' the several pipes 13, 27, and' 19 areindicated at 32, 33, and

34: respectively on a dial 35 tornied 'integrallv with a bracket 36 on which the valve nipulatng the manipulating valve 17. i For i this purpose a nanipulating ha'ndle 37 is' secu'red to an extension 38 of the manipulating.

valve 17 and is held in assemhled position by a pin 39 which extends' through theex.-

tension 38 and the' handle 87. A ponter l0 V is preferably formed integrally with the handle 37 and is ofa length to extendto'a point adjacent the indicators 32, 33 and 34 i for indicating the positions themanipulating valve occupes-` in` practice.

In order that the manipulating valve may be securely held inplacedi position, a

release handie 41 is pivoted thereto to operate With Slots 4:2 in the valve chest 16 suitably located With-respect-to' the difl'erent positions of the manipulating vaive. A

spring 43 seatedin the handle37'loearscon-` stantly against the release 4 handlefor holding said handle'n engagenent with ,the

` r r l-'froni which 'leads a vent 4c5controlled in Forned inthe head'p is aclearance pocket this instance-by an equalizer valve 46 slidable ina valve chest'? Secured to the head y) in any suitable mannex Ai passage 4:8 formed" transversely through the' equalizer valve 46. connnunicates With a; passage 49' leading to 'the rearward end of thev-alv 46 N to permit the entrance of pressure fitudinto a' chamber 50, Wherein= thesaid. valve' is adaptedzto reciprocate for nornally holding said valve' closed. Pressure fluid thus acting againstthe valve for` the purpose` described is also augmentediby a: spring 51 constantly hearing on the valve for holding it to its seat., In the present instance an adjusting plug 52 carrying a spring seat 53 for one'end of the spring 51 is screWed into the end of the valve chest 47 for: adjusting the tension ofthe spring 51'. A cap nut 54 soreWed-on the 'end off the adustingplug 52 serves the i dual purpose of looking the adjustng nut in position 'and also se'als the chamber 50. A

pipe55 leading fromthe valve -chest47 serves to convey i pressure fluid fronrthe chambereo to the' passage s: in 'the head; p wheneverxthe equalizer valve is unseated by. pressurefluid in the ciearance pocket 4:4.

An intake unioader 56 is provided for unloading and; loading: the fourth stage' oylinder Q).

leading froni the' interoooler Pressure fluid' thus flowing" from the ntercooler u through the pipo 59 and the passage 58 is' convey'ed through a= passage 60 in-.thehracket.

'57 which conimunicates With the passage' 5 in the heads. A hore l istormed in the bracket- 57 'preferahly in line With thepas sagra-5& to receive a valve guide 62 bored to receive slidably a p1unger63 which Cooperv ates with a v-a-lve seat 64 inmhe valve guide 62 for controlling the fiowfot pressure fluid froni the passage 58 into the-passage60 and, consequently into the -cylinder u; V

Any suitable' and' oowenient means inay be providedfor securng the valve guide 1nt the bore 6l .In thepresent instanc'e an; ex#

ternally threaded' nut 65 is boredto receive slidahlv the valveguide 62 and'is` screwed Ilt-Ora threaded aperture-66 in the br acket 57.

A fiange67 'forined in` the outer endsofthe p This' intakeunloader coinprises brachet 57 seated on thehead a: and' lias a passage 58 in communication With a pipe 59 nut- 65' abutsa shoulder=68of theva lve guide 62 for' holding the valveguid e' in'- postion r lum-der to prevent the escape of any pres-f sure-fiuid which may'lea i'z along the plunger p 63 to the atnosphere, a check valve 69 is placed inthe valve guide 62 rearwardly off the plu'nger 63-to reston'a seat' 70 in the va'lv-e-guide when the plunger 63 is openedto adnit pressure fluid from-the intercoolereinto-the eylinder v. r v

Supported by' the bracketq' ist-an unloader cylinder 71" having a cover 72-'secured to the outer end'thereof in any'suitable man: i

ner. In` this unloader cyiinder 71' isarranged aj piston 73WVhiCh abuts a Valve-sten 74 of the-checkvaive 69 and` is adaptee to;

slide in a reciprocable piston head' ar-' the head e." The body 78- has a passage 79." t

which comniunicates With`a`passage-80 inthe i head e leading from thepassageG commu-` nication betweenrthe passagesfland 80 being e controlledzby the discharge yti-we r; r e

Disposed ina a; bore SLofthe body. 78vis a I "valve cage82;in which is arranged a valve 83 to\ control a passage 84 coinmunicati'ng Withthe passage: 79;, ThGValVQS in this nstanoe has an end head: 85 WhiCh; is: adapt- 'edtoahut ajpiston 86slidableina-bore 'of` e i u a buShingSS. The bushing& in this n I stance 5 also: serves to hold the val've cage s' in; assemhled position; A recess 89 is; fornied' in;the inne'r end-of: thepiston 86 toreceveaspring 90 seated at, one end 'against the end Wallet-the recess 89and With its' other end" i llO on: the head 85 of the vaive 8-3., Dhe bushin g 88 and the valvecage 82 may' beheld'securely in asseinbledjposition in any suitable 3 lnanner. In thepresentainstance a coliar 91' s arranged about the bushng i 88 to ahut a ,flange 92 of the said bushing and; b0lts-93 extending through the'collar 9l are screwed into the end of the body. 78@

Azclosure forthe' -endof the hushing 88-is ?i ina this instance provided in thefor-in' of; a, plug Qthaving a passage which connnu- V nicates itlrthe-bore 87 ofjthe bushingBSL A pipe596leading from-the passage 60'in the bracket.. 57 to the plug 94: serves to cenveypressure fluid'to the bore-87 for actuating -the-piston-i-toclosethe valve`83. p v

'Dhe meanswhereby pressure fiuidmay-he pi'ston: head? 75 and the piston 733 to close the plunger, 63 in this-instance consistszof a pipe 97 leading fron ja valve chest 98' i adinitted intothecvlinder 71 to actuate the i i tween the pipe' 97 a-nd an exhaustgport' 103 in:

i f m the valye chest 98 for ezdiausting'pressure a fluid 'jfromthe cylinder 71 ,to the atmos- 7. phere. The -manipulating valve 99,'like the 'nanpulating valve 17, is also provided With a handle 37' 'or rotatng thesad manpulating ValVe and 'the ponter 4:0* to cooperate 106 fon indicating the 'positions which .the valve is intended to occupy 111 practice.

*In the present instance the regulator body 8 alsoacts as a housing for 'a check valve 1107 ;of aknown typeslidahleiin a valve seat 198 9 to 'control 'communication between the i passage' 79 and a discharge passage 109 i'n- &the body 78 'A spring: 110`acting 'against t-l1e-` ValVe 107 aCtStOhOld the valve closed for pi 'eyenting the return of pressure fluid from afinal receiver tanl' 111 communicatate. the compressor under 'full .load condi- I 'i 'j tionsr fn such case the inanipulating valves i 17 and..9`9 :Willy occupy: the positions' illustrat' ed in Figres '3, tand In'these posi ;froni the 'service pipe l8 'through the passage i; .ppes l and 19w il`lfbe opened:to the' atmos- 'ph'ere through the 'ecesses' 31 -and29 and ;through exhaustports e md lltvrespec- "afiij st' andfsecond stage 'cyli'nders are free to function in their normal nanner Without being iinpeded 'by the fingers 9of the 'un loader pistons 7'.- r

When operating under full". load,` the -phere'through %the pipe 97, the recess 102 v fiplunger tooccupy itsopen position, for

adinittingpressure fluid' nom the; passage r 581' into; the passage and thencethrough zi'th'epass'age into the scylnder v; While the' plunger isopen,'ap`ortionof the'pressure *fluid ente'ring the passage 60 from the pas-' ppe 96 and i sa ei, 58 'flows through; the V i through' the 'passage'f95in' the plug 94' and acting 'against the 'piston: 86 forces the 'valve With indicators 104 and 105 of aa-dal platc'j in in this instance W-ith the passage 109 The operationof .th device is as folloits: v Let it he assumed that itis' intended to oper tions ofthevalves' pressure fluid will flow 28 of; the valvej17 ;and through the pipe' `?27, into the cylinder `2L to act i against the&` ,pistoni25for holding the jValVe 20 closed. Vhenthe Value 17 occupies this position, the` yely in theLvalve chest -16. 'It willthere' :tote 'he seen that the inlet valves of the ,loadercylinder 71is i also' open to the atmosintheivalve 99 jandfthr ough the' port' 103" Sin the Val've' chest 98, thu's permitting the a 83; .to 'its seatjand thus cutsofi communica tionhetween thepassage 79 of theregulator body 78 and an ati'nospherio vent 115 in said body 78. r

If IIOW,1OI' Well; known reasons, t he desired to unload the 'fourth stage cylinder e, the manipulating Valve 99 may be rotated 'to Carry the po1nter40 to the'indic'ator 105.

In this position of th e'nanipulatingvalve 99, the .passage 100 Will estahlsh communication between the pipe 101 and the pipe '97 and'c pressure fluid Will thusfiow intothe cylinder 71 and, due -to the pr'eponderance ofarea of the piston-head 775 over the-end of the plunge'. 3, .will force said plunger to lS seat'aganst the relatvely higher pressure fiowing 'roni the intercooler u. In this also the supplyf of pressu'e fluid actin'g be'cut-Ofi. i

.After the supply ofvpressure fiuid to the cylinder 'o has, been'cut-ofiythe piston a; Will draw a Vacuuin and any slight amount of 2111 1 o XVlll be exhausted through the passagesfi, i I

which might find its Way into thecylinder 'ainst the piston 86 in the bushing'88 Will r .way communication between the .intercoole' i u andthecylnd'er v Wlll he cut-oli' and thus 80 and 79 andthroughthe port 84: to' move; the valv'e 83' froni its closed position'and thence escape 'to the atnosphere through the 'vent 115, lVhenthefourth stage cylinder v is Operating under' these conditions, the

spring in the piston 86 Will force the pis ton 86-'and the Val e 83 apartso that inthe hsehce of pressure' fluid in? the bore 87 of the hushng 88,the,valve 837 Will' function passages 79 and 80.

' lVheneverthe conipressed air delivered jfroni the third stage'cylinder to the receiver tank or intercooler uexceeds' certain-pre deterniined pressure ai'd it is found desh able. to reduce the 'Volume discharged into' the reoever tank, the cyhnder chainbers .in

as an? ordinary {check Valve to alloW the pas sage of from the .cylnder to the atmos- W 'phere through the ventll and to `prevent the' adnission'of atmospheric 'air' into the g j one or the other of the cylihders' BY and ,C i

Let it be assumed then that itg be decided tonnload the first stage cylinder chanber G- and the internieeiete stage cylinder H. To accomplish this the'nianipulating ValVe 17 may he rotatedsothatlthe pointer 'tO'Wlll coincde Withthe indicator 34. In this position 'of the inanipulatingf 'valve 17, pressure fluid froni the pipe 18 -Wlll pass through the rec'ess`29, thepassage 30 in the :Valve chest and through the pipe 'may be unloaded-until the pressurc in the recevertank has been reduced to a desired Value.

19 to act upon the ends of the unloader *1,25

pistons 7.' These pistons 7 'Will he thus r forced forwardly s'o 'that the fingers 9 ill,

bear upon 'the 'valve platc s 10 andhold the said; alve plates open; In thisWvay the piston F in 'the cylinder B Will reciproeate in the `cylinder C Without doing any actual Work of compression. I

It Will .be noted that When thenanipu- .lating alve l7ghas beenlrotated'to the ;posi- .tren for adinltt ng 'pressure fluid 'into the ppe 19, the passage 28 `in i the mani pulating chest 16. .By th'us exhaustingthe pressure fluid from thecylinder 24,t-he ValVeQO Will be permittedtoopen so that a portion of the air in the cylincler j maypass into the clearance pocket44 `While the remaining portion r s, of course, exhausted through :theexhaust Valve m to flow through the passage send the 'pipe t, into the inter cooler u'. a

While the manipulating valve 17 istin the position described With pointer at;position 34, the unloader pistons 7 of cylindersJ and 'K Will fbe .in the tout position due 'to exhausting of air behind them throughthe pipe 13, passage 31 and atmospheric, vent 113. Thus the inlet valves Q, and d .Will functionto 'allow the cylinders J and K to operate under fullload. f i I v Frequently in manoeuvring Vessels otthe type employing compressors to which the 'present invention is appliechdt so :happens that sudden unusual demands'are made on' the Volume of compressed air in thereceiv er tanl; 14,' thus causing a considerable drop i n pressure insaid receiver' tank as Well as in the cylinderj j. If, then, immediately prior to such demand, the cylinderj has been Operating at one-half load and discharging into {the `'clearance pocket 44,'the clearance valve 20 Will close' immediately uponthe occurrence .of a drop in pressure n the cylinder `j. Vith 'these conditions obtaining the pr-essurewn the clearance pocket 44 may be of higher Valuethan the pressure in the cylinder jand it is possible that theaclearance Valve 20may .be held shut by 'the .pressure acting on;the 'differential area &of the reverse side of the valve 20 so that it 'Will not open When pressure ffluid :is exhansted from the cylinder 24. Howevegfiwith the pressure fluid in the receiverltank, as Well as in the pipe t and the passage s, of lower Value than the pressure entrapped in the clearance pocket 44, .the equalizer valve 46 Will open and the entrapped pressure fluid will flow from the clearance pocket 44 through the pipe 45 and the pipe into the passage 8.

Thecylinder chambers J and K of 'the cylinder C may be unloaded in the manner described in connection With the cylinder cnambers G and H, it being merely necessary to rotate the manipulatng valve 17 so that the recess 31 in the manipulating valve registers With .the service pipe ,18 and With i .the pipe .13 foradmitting .pressure fluid to ;act- .aganst the u'nload'er ,pistons 7 of the second and` third. stages' 'of the compressor k may bennloaded or loadedby single valve Conveniently and centrally locatedon ;the

compressor. The means,;such as thevalye 17 and the various cunloading devices, pro-` vded tor controlling, the loadng of thedif- :terent cylinders is, ineflect, interlOching,

that is the .nnloading devices of the several' oylinders Willhe Jcaused to function in .the proper" order' and' at the most suitable y period in .the :loading :and unloading Operations.

For nstanewhen the ValVe 1'? ris rotated to" unload either of the first and :second stage y cylinders ;the thrd stage cylinder y' Will simultaneously be partially unloaded to" compensate for-the reduction in the load .of

the lower :stage ucylinders. :Due :to z this fact the uncertainty heretofore experienced as .to the proper ;functioning of the unloading de-'- yices by the operation ofa nultiplicity .of :control yalves, handles andthe ;like has been entirely :eliminated The positions' which themanipulating valve 17 lS supposed to occupy for unloadng 'or loa-cling the several l tages is .plainlay .indicated on' the da-l' and the man-ipulating valve l? .may there- .forebefreely manipulated:Without .causing v 'injury to'the' compressor. p Iclain: i "i y i 1. In :a mult-sta ge compressor, the combination of cylinders Operating at different. pressures, fluid actuated means =for`load1ng and unloading theeylinders, and means tor select-ively cont rolling ?the admission 'and eXhaust of pressure fluid to andfrom said -fluid actuated means i 2. In a-multi-stage`compressor, the combination :of cylinders :Operating at different pressures, *fluid `actuated means *fo-r :loading and unloading the cyli nd'ers,`and manually operableimeans-forselecti ely controlling the admission andexhaust ofipressure' fluid to and from said'fluid actuated neans.

leo

3. In a multi stage compressorg the com- 4 bination of cylinders Operating at difi erent pressures, fluid act-uated means in the cylinders for loading and unloading the cylinders, and centrally located 'interlocking means remote from the cylinders for selectively controlling the admission and exhaust of pressure fluid to and from said fluid.

actuated means.

4. In a multi-stage compressor, the combination of a pair of cylinders Operating at a low pressure, a cylinder Operating at a higher pressure, a pair of intermediate pressure cylinders, and fluidactuated means for 'simltaneously unloading' i a low pressure j ;afer partally unloading the higher pressure cylnder; v 5.`;In a,mu1 ti-stage compressor the' coma 'l bination'of apainof lowpressurecylinders,

7 fja paiiof'intermediate 'cylinders connected toreceve pressnre figd from the ?low pressure ilcylinders, afhighen 'press'ure cylinder c'onne'cted to receive pressure fluid-from 'the "eylndel gpl'essureiactuated means orgun fseating the' inlet valves of'the low and in- .te mediate cy1inders, a clearance valve for 'the: higher pressure cylinden 'normally het d iclosedhy pressrefluchand a manipulating valve rotatable toonepositionfor admittin'g pressure fluid to 'the pressure actuated means 'for holding the inlet valves at one low pressure' cylinder: and one intermediate cylin t lider open tounioad said'cylinderst and toi* smultaneously exhaustng p'i'essure fluid acting upon the clearance valveifor'partially inanipniating 'valve also being rotatable to another 'position tor admitting pressure fluid ;t'othe pressure actuated means for holding the inletn`valves.. of the othenlow p essure and intermediate pressurecylinders open and for jsiin'iiltneuly exhausting pressure fluid acting upon the clearance valvetor partiatly inl'o'ading the higher r pressure cylinder. r j 6: .In amult-,stage compresso the comcyl in ders a t third stage cylinder connected to r'eceivegpressure fluid from thesecond stage' i r i cylind'ers, a ourth stagecylinder connected c; torece've pressu e flmd from the thu-d stage cyhndey,pressure 'actnated means for conatrolling communication between the thrd f: fcr unloadingthe fourth 'stage cylinder.

7.; 'In a inultistage compressr,: the com- ;hntion of a paif of first stage cylinders, a pair cfsecond stage cylinderslconnectd to receive pressure-;fluid from the first stage i -ylinders, a thi'd stage "cylindr' connected ,receive pressre .fluid. :from the i second -eylinder and an intermediate cylnder and internedi ate cyliiders; 'in-let Valves for the ,nnioading the higher pressure cyiinder, said" E -bination` of apair of first stage cylnders, a 'i par of second stagecylnderscoinected to ;receive pressure flu1d-trom; the first stage' and foi'rth stage cylinders,and ,means for' selectvely cont'rolhngthe adnnsson of pressure fludvtogthe pressure actuated means stage cylnders, a oui'th stage cylinder connected to receve pres'sure 'fluid from the thrd stage cyhnder, pressure actuated means 'for controlling communication between the I thirdand fcurth'stage cylinders, and ama- .nipniating valve rotatahle to one position toi' adnttng'pressure to 'the pressure actuated 'means for unloadingthe' fourth stage cylindei', said nanpulatng Valve also bengrotatable to another position to exhaust pres i sure fluid from the pressure" actu'ated" means 'tor loading the fourth stage cyhnder.

8. Ina multi-stage compressor, the com binatio n of a final stage cylnder and cylindersoperatngat lower pressures, means :for conveying pressure fluid from a lower 'stage cylinder tothe final 'stage cyiinder, an unoadencylinder, a pressure fluidactuated niunger in thennloader cylnder tor controiling the adinisson of pressure'fluid from v said means to the' final stage cyhnder, a

manuaily opel'able valve controlhng the 'admission of pressure fluid into` the' unloadei' 'cyhnder' to close the phnger 'for unloadng the final stage cylindeyand means associated i With the final stage cylinder for automatically and nteriockngly establishing communication between the said cylinder and the atmosphere during the unloajded 'period of the final stage cylinder. v e

I 9. In' a hamiti-stage compressof, the 00111 hination of cyln'de'rs Operating' at different ,pressu res, connections for establishing c0n1- munication between cylinders 'of successive stages,' a valve chest, a valve in said chest adapted' to estabhsh commun cation between the cylinder .Operating at highest pressure and the atmosphere, said valve 'being held closed by pressure fluid during the'operaton of the high pnessure cyhn'der, an unioader i cylinder, a plunger in the unlcader cylinder' to .control the adn sslon of pressnre fluid nto the high pressure cylnder and nto the valve chest,. and a. manualiy oper'able vali/e controlling' the admission .and. exhanst *of i pressure fluid to and from* the unloader cylinder. "to close and open the plu nger for' unloadng and loading the high pfess'ure cylinder.

' -,In testimony ivhereof' hane'sign ed this specification.. -V i r I SNOWDEN B. REDFIELD. 

